From 92ae117a209d5b222c5e9c8a043893846b85b36b Mon Sep 17 00:00:00 2001 From: Peter Collingbourne Date: Wed, 15 Sep 2021 12:03:35 -0700 Subject: [PATCH] UPSTREAM: arm64: add MTE supported check to thread switching and syscall entry/exit This lets us avoid doing unnecessary work on hardware that does not support MTE, and will allow us to freely use MTE instructions in the code called by mte_thread_switch(). Since this would mean that we do a redundant check in mte_check_tfsr_el1(), remove it and add two checks now required in its callers. This also avoids an unnecessary DSB+ISB sequence on the syscall exit path for hardware not supporting MTE. Fixes: 65812c6921cc ("arm64: mte: Enable async tag check fault") Cc: # 5.13.x Signed-off-by: Peter Collingbourne Link: https://linux-review.googlesource.com/id/I02fd000d1ef2c86c7d2952a7f099b254ec227a5d Link: https://lore.kernel.org/r/20210915190336.398390-1-pcc@google.com [catalin.marinas@arm.com: adjust the commit log slightly] Signed-off-by: Catalin Marinas (cherry picked from commit 8c8a3b5bd960cd88f7655b5251dc28741e11f139) Bug: 187129171 Signed-off-by: Connor O'Brien Change-Id: I206eafcb65577117853a491c373a2abf849f4a2b --- arch/arm64/include/asm/mte.h | 6 ++++++ arch/arm64/kernel/mte.c | 10 ++++------ 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index 58c7f80f5596..c724a288a412 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -105,11 +105,17 @@ void mte_check_tfsr_el1(void); static inline void mte_check_tfsr_entry(void) { + if (!system_supports_mte()) + return; + mte_check_tfsr_el1(); } static inline void mte_check_tfsr_exit(void) { + if (!system_supports_mte()) + return; + /* * The asynchronous faults are sync'ed automatically with * TFSR_EL1 on kernel entry but for exit an explicit dsb() diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 20a40e5a14fa..128c442a848e 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -176,12 +176,7 @@ bool mte_report_once(void) #ifdef CONFIG_KASAN_HW_TAGS void mte_check_tfsr_el1(void) { - u64 tfsr_el1; - - if (!system_supports_mte()) - return; - - tfsr_el1 = read_sysreg_s(SYS_TFSR_EL1); + u64 tfsr_el1 = read_sysreg_s(SYS_TFSR_EL1); if (unlikely(tfsr_el1 & SYS_TFSR_EL1_TF1)) { /* @@ -233,6 +228,9 @@ void mte_thread_init_user(void) void mte_thread_switch(struct task_struct *next) { + if (!system_supports_mte()) + return; + mte_update_sctlr_user(next); /*